Acoustic reproducer horn suitable for use with radio sets



Dec. 3l, 1929. P. E. EDELMAN 1,741,508

ACOUSTIC REPRODUCER HORN SUITABLE FOR USE WITH RADIO SETS Original FiledJune 5. 1922 :naman 4 Z 5 i INVENToR Patented Dee." '31,1929

UNITED STATES PATENT OFFICE PHILIP E. EDELMAN, OF CHICAGO, ILLINOIS,ASSIGNOR TO EPHRAIM BANNING, OF CHICAGO, ILLINOIS ACOUSTIC REPRODUCERHORN SUITABLE FOR USE WITH RADIO SETS Original application led June 5,1922, Serial No. 566,132. Divided and this application filed November28,

An object ofthe present invention, which is divided from my originalapplication S. No. 566,132 filed June 5, 1922, is to provide areproducer horn of better tonal qualities substantially free from aircolumn resonance and without distortion effects. I accomplish theseobjects by a novel construction of the reproducer horn whereby the crosssectional area of the horn progressively increases along its length sothat for predetermined equally spaced intervals along such length suchcross section is substantially doubled, while at the same time thethickness of the wall of the horn preferably increases in similarproportion, being thin at the small end and increasing in thicknesstoward the large end as the thickest Wall portion.

,My invention is illustrated in the accompanying drawing in which thefigure is a longitudinal section through a horn embodying the invention.

A holder 1 contains the reproducer unit 4. Cord wire 5 connects withunit 4 to actuate it. A support 2 holds unit 4 against a yielding gasket7 in holder 1. Gasket 7 corresponds in contour to the cap 9 of unit 4.Support 2 is held to holder 1 by screw 3. A channel 6 is provided inholder 1 to accc umodat cord 5.

The reproducer horn 12 has a taper neck portion 10 wedged to fit intoholder 1 at opening 8. Horn 12 has an orifice E. The wall 11 of neck 10increases progressively along the length of neck 10, beinig the thinnestnear orifice E. The cross section area of the horn portion 10 increasescontinuously starting at orifice E so that such area is approximatelydoubled for each such predetermined successive interval along the lengththereof.

The goose-neck portion 13 of horn 12 is similarly proportionedcontinuing from neck portion 10 so that the wall thickness ot gooseneck13 increases progressively as the distance away from orifice Eincreases, while the cross section area of said horn also continues toincrease at the same rate as in the case of throat neck portion 10 up tothe orifice portion D.

A bell portion 14 extends from goose-neck portion 13 and similarly hasitswall thick- Serial ness progressively increased along the lengththereof while the diameter increases in a ratio per unit lengthapproximately the same as for goose-neck portion 13, the largest crosssection being at C, and greatest wall thickness at F.

Vood or wood fibre is suitable for making the horn 12. The air columnstarting at oriiice E and continuing to rim 16 of bell portion 14 isthen confined byprogressively increased Wall sections per unit lengthcorresponding to increased cross sections per unit length from orifice Eto rim 16 so that air column resonance and pick-up of secondaryvibrations from the horn 12 is substantially avoided. The junction ofportion 14 to gooseneck 13 at 17 must be smooth. Radii to secure theaforesaid proportioning can` be located as indicated by M, K, J, L, H,and G. rThe dimension A is greater than the dimension B. By suchproportionment clear and true reproduction can be obtained from horn 12under control of reproducer unit 4 which may be actuated for example bya radio receiving set.

It is permissible to depart somewhat from an exact doubling of crosssection at equal intervals along the length'of the horn, especially atthe bell portion 14 but the wall thickness should in such case becorrespondingly changed to preserve the relative proportions of the aircolumn area at any particular unit cross section to the thickness ot thewall of the horn 12 at such position. The marked iinprovement of suchconstruction will be noticed especially on reproduction of organ musicand bass notes but the absence of tinny or high pitched sounds due toactions between the horn 12 and its air column 15 is also pronounced,leaving the vibrations of air column 15 substantially wholly undertheinfluence exclusively of the reproducer unit 4 whereby undistortedamplification is attained through said confined air column.

While I have shown and described but a single embodiment of myinvention,it is to be understood that it is capable of many modications. Changes,therefore, in the construction and arrangement may be made which do notdepart from the spirit and scope of the invention as disclosed in t-heappended claims.

I claim:

l. An acoustic reproducer horn having input. and output orificesterminating a restricted air column, the cross section area of said aircolumn increasing progressively from said input orifice to said outputorifice so that for predetermined successive equal intervals along saiddistance 'therebetween such cross section. is substantially doubled.

2. An acoustic reproducer horn having a restricted air column andconfining wall therefor, an input and an output ori ce for said h orn,the cross section of said air column increasing progressively from saidinput ori- .fice to said output orifice at a rate which approximatelydoubles the area thereof for predetermined successive equal intervalsbetween said orifices, and the thickness of said wall progressivelyincreasing proportionately, the

greatest thickness thereof being near, said output orifice.

3. Anv acoustic reproducer having a restricted air column and confiningwall therefor with input and output orifices, the cross section of saidair column continuously doubling in area for successive equal incrementsalong the length of said air column while the thickness of said wallproportionately in-.

. output orifices,'the area of said air column at said input orificebeing theleast and progressively increasing by increments to thegreatest area thereof at said output orifice while said wall similarlyincreases in thick ness by proportionate increments, each successiveincrease ef air Column area being bounded by a wall portion of similarlysuccessively increased thickness.

6. An acoustic reproducer horn consisting of a confined air columnretained by a wall with the input and output orifices, the cross sectionarea of said aircolumn increasing progressively by increments along thelength of said air column whereby said area approxi'matclyv doubles forpredetermined successive equal intervals along said length, and thethickness of said Wall correspondingly increasing by increments,beingthicker for each successive increment corresponding to saidincrease of air column area, and an ac-V tuating reproducer unit held inposition at said input orifice.

In witness whereof, I have hereunto set my hand this 13th day of Au ust,1927.

PHLIPE. EDEL AN. [1.. s]

